Presentation on theme: "Energy Dissipation at Foundation Level By: A. Mahdizadeh N. Goudarzi 6 th International Conference of Seismology & Earthquake Engineering (SEE6) May 16-18."— Presentation transcript:
Energy Dissipation at Foundation Level By: A. Mahdizadeh N. Goudarzi 6 th International Conference of Seismology & Earthquake Engineering (SEE6) May 16-18 Tehran, Iran
Contents Introduction Sliding of Masonry Buildings Observation in Past Earthquakes Principles of Base Isolation materials Methods of BI in Masonry Buildings Shake Table test of a Masonry Buildings Rocking Behavior of Shear walls Effects of Rocking Foundations Experimental Research on Rocking Shallow Foundations (B. Kutter 2006) Analytical study of Rocking Shear walls (B. Chang 2006)
Introduction Current Practice in Structural Design 1.Modeling and analysis of structure with fixed base assumption. 2. Analysis and design of foundation using the reaction forces of the superstructure model. Disadvantage of Fixed Base Modeling High cost of foundation
Sliding of Masonry Structures on Foundation Sliding has saved URM Buildings from Collapse. (Gee 1934) In Tangshan Earthquake (1975) a horizontal crack saved a masonry building. In Wuchang Earthquake (1960) a horizontal crack saved an old earthen building. 85% of other buildings collapsed.
Weathering Necking cracking In Wuchang Earthquake (1960) a horizontal crack saved an old earthen building. (Li 1984)
In Xingtai Earthquake (1966) a horizontal crack on the second floor saved a URM masonry milling plant. Unplanned sliding of adobe buildings saved the majority of them in Bouhai Earthquake 1969. If Horizontal Cracks can save buildings, Why not make them beforehand!?
Principles for design of BI in Masonry Buildings Effectiveness Economy Endurance Ease of Construction
Methods of Base Isolation for URM Buildings Sand Slide Slit Base Isolation Measure (Li 1984)
Rocking Behavior of Shear walls Fixed Base modeling of Shearwall structures: Costly foundations in low-rise buildings With considering Rocking of Shearwall: More Economical Foundation design Adequate ductility and damping
Uplifting Geometrical Nonlinearity Yielding in Soil or Foundation
Detail for controlling settlement (T. Paulay, M. J. N. Priestley, 1992) Concrete Block
Detail Concrete Block (T. Paulay, M. J. N. Priestley, 1992)
Experiments on Shallow Foundations Supporting Rocking Walls (S. Gajan, B. Kutter, 2006)
Conclusion Base Isolation of URM buildings at foundation level enhances seismic performance of these structures. BI of masonry structures can be adopted for retrofitting to reduce cost of rehabilitation at foundation level. When adding Shear walls for retrofitting, rocking could be accounted for to reduce cost of rehabilitation at foundation level.